Local messages received X hours or even 1 day after....

[albatroz]

A customer has reported that when she sends email
to certain users of her same domain, they are received
after several hours, even 1 day after.

This is not a general problem, but an isolated issue.

Has anybody experienced this problem before? If so, how could
I detect this issue and solve it?

Thanks in advance any help you may bring to me

 

[toml]

There are a lot of reasons this could be happening. The first thing, is this customer using the SMTP server for that domain or thier ISP? If it is the domains SMTP server, you should be able to follow the path of the message in the /var/log/exim/mainlog file. If it is the ISP's SMTP server, then you need to pay attention to when the message reached the domains server and was finally delivered, it should never be more than a few seconds. If it is taking the ISP hours or days to deliver messages, then there is almost nothing you can do, other than work with their ISP to resolve the problem.

Also, one last thing you should really do is to plug the domainname into http://www.dnsreport.com/ and verify that your DNS is working properly. If it is not, then that is most likely your problem.